Known as a high polymer having ferroelectricity, copolymer P [VDF/TrFE] of vinylidene fluoride (VDF) and trifluoroethylene (TrFE) has good piezoelectricity and large spontaneous polarization (residual polarization) and is being investigated of its application to a variety of elements and devices such as a piezoelectric sensor/transducer and an infrared pyroelectric sensor on making use of its flexibility and machinability. In patent documents 1 and 2 published, there are proposals on piezoelectric films made of mixtures (blends) of copolymer P [VDF/TrFE] and fullerene hydroxide and/or carbon nanotube.